1. Field of the Invention
The present invention relates to a method of loading a magnetic head for use in a magnetic recording/reproducing apparatus that allows data to be recorded on a magnetic recording medium and to be read out from the magnetic recording medium by means of a magnetic head. The present invention also relates to a magnetic disk drive unit using a magnetic head.
2. Description of the Related Art
FIG. 7 is a perspective view showing a conventional magnetic disk drive unit. In FIG. 7, reference numeral 1 denotes an arm, and 2 denotes a flexure consisting of a leaf spring and mounted on the arm 1. The flexure 2 is adapted to be bent near the bonding section thereof with the arm 1. Reference numeral 3 denotes a gimbal disposed on the front end part of the flexure 2, and 4 denotes a magnetic head fixed to the gimbal 3. The magnetic head 4 is constructed as shown in FIG. 8. In FIG. 8, reference numeral 4a denotes a slider main body composed of a magnetic material of ferrite or the like. On the slider main body 4a, a U-shaped float rail 4b that causes generation of a positive pressure is disposed, and on the float rail 4b, depressions 4c are formed. Reference numeral 4d is a recess surrounded by the float rail 4b, and a negative pressure is generated in the recess 4d. Reference numerals 4e and 4f are cores bonded to the slider main body 4a via non-magnetic materials 4g and 4h, respectively, which serve as magnetic gaps. Reference numeral 4i denotes a lead wire wound around the core 4e. In this case, only the core 4e performs magnetic recording and reproduction. Air flows toward the side (the downstream end B) on which the lead wire 4i is wound from the opposite side (the upstream end A). In FIG. 7, reference numeral 5 denotes a flexure pressing member mounted on the arm 1 and abutting against the flexure 2 on the side remote from the disk 6. The flexure pressing member 5 is formed of a wire made of a shape memory alloy, being bent in the form of the letter V. A shape is memorized in this flexure pressing member 5 so that the latter presses against the flexure 2 when its shape has recovered so as to displace the magnetic head 4 toward the disk 6.
The operation of the magnetic disk drive unit constructed as described above will now be explained. First, the loading time will be explained. At first, the magnetic head 4 is held so that it is separated from the disk 6, as shown in FIG. 9A. Next, after the rotational speed of the disk 6 reaches a predetermined value, the flexure pressing member 5 is energized. Then, the flexure pressing member 5 itself produces heat and brings about a shape recovery. Then, the flexure pressing member 5 presses against and bends the flexure 2 toward the disk 6, bringing the magnetic head 4 closer to the disk 6. This circumstance is shown in FIG. 9B. Next, when the gap between the magnetic head 4 and the disk 6 reaches a predetermined value, the flexure pressing member 5 is automatically deenergized, thereby causing the flexure pressing member 5 to cease pressing against the flexure 2. However, if the magnetic head comes to this position, a negative pressure that brings the magnetic head 4 close to the disk 6 is generated in the magnetic head 4. If the magnetic head 4 comes too close to the disk 6, a positive pressure is generated in the magnetic head 4. At this time, the negative pressure balances with the resultant of the positive pressure and the force which urges the magnetic head 4 to move away from the disk, so that the magnetic head 4 enters into a floating state. These circumstances are shown in FIG. 9C. When a predetermined recording or reproduction operation by the magnetic head 4 is terminated, the rotational speed of the disk 6 decreases, and the magnetic head 4 is lifted off from the disk 6 by the recovery force of the flexure 2. The magnetic disk drive unit constructed as described above is designed such that when the side of the magnetic head 4 opposing the recording medium is nearly parallel to the disk 6 after the magnetic head 4 is brought closer, the magnetic head 4 floats exactly on the disk 6.
In the conventional method described above, however, since the magnetic head 4 comes closer to the disk at downstream end A, the magnetic head 4 moves perpendicularly to the disk 6 in the air flow area formed on the surface of the disk 6 by the rotation of the disk 6. A sufficient positive pressure is not generated in the magnetic head 4 by the time the magnetic head 4 reaches a floating position, and the magnetic head 4 is urged to make contact with the disk 6, thus sometimes causing damage to the disk 6. Therefore, the area in which the magnetic head 4 can float during a loading time must be formed on the disk 6. A problem arises, however, in that, namely, the storage capacity of the disk 6 is insufficient. It may be considered that the magnetic head 4 is gradually brought closer to the disk 6 in order to prevent the magnetic head 4 from making contact with the disk. However, a problem arises, in that, namely, the loading time is increased, thus reading and writing of data are delayed.